Predictions for Chemistry 2014 HSC? (6 Viewers)

[faisalabdul16]

New Question: Describe and explain the exothermic nature of sulfuric acid ionisation (Industrial)

Energy released to make bonds is greater than energy required to break bonds. (someone check this, I have a feeling it is wrong.)

<img src="http://latex.codecogs.com/gif.latex?H_2SO4(aq)&plus;&space;H_2O(l)\rightarrow&space;HSO_4^{-}&plus;&space;H_3O^{&plus;}&space;\\\\&space;HSO_4^{-}&space;&plus;&space;H_2O&space;\rightleftharpoons&space;SO_4^{2-}&plus;&space;H_3O^{&plus;}" title="H_2SO4(aq)+ H_2O(l)\rightarrow HSO_4^{-}+ H_3O^{+} \\\\ HSO_4^{-} + H_2O \rightleftharpoons SO_4^{2-}+ H_3O^{+}" />

 

[Cleverusername5321]

Alright, lets go

- Before WWI, one of the main source of ammonia for use as fertilisers was from saltpetre from Chile.
- During WWI, these supplies were cut to Germany and thus, they required a new method of obtaining ammonia for essential food production.
- The Haber Process provided a way for ammonia to be formed from gaseous nitrogen and hydrogen and was essential at that time for Germany, as it provided fertiliser and thus food for their population, preventing mass starvation.
- Ammonia could also be used to produce nitric acid which was in turn used to make explosives and so the discovery aided Germany's war efforts.
- Therefore, Haber's discovery was essential for Germany as it provide food for its people and weapons for the war, essentially prolonging WWI.
- However, after the war, this new method of obtaining ammonia was adopted worldwide and today the sheer importance of the discovery is evident as the Haber Process is the main source of ammonia, which is used for fertilisers in order to feed our continually growing population. This high demand for ammonia and fertilisers would not have been able to be provided by natural sources such as saltpetre and guano and thus the importance of the Haber's discovery.

I'm pretty sure they wouldn't care, but I don't think that's fully correct. I think the Haber Process was introduced at something like 1910, whereas the blockades occurred in 1916 or maybe 1917. So it was already there prior to that.

 

[zhertec]

New Question: Describe and explain the exothermic nature of sulfuric acid ionisation (Industrial)

Assuming this is something like a 2 marker.

The exothermic nature of sulfuric acid is due to the difference between the amount of energy required to break the bonds and the resultant energy released from the formation of the products. Sulfuric acid is much more stable in ionised form, although the ionisation of sulfuric acid in water is slightly endothermic: H2SO4 (l) --(H2O)--> H+ HSO4-, the reaction between hydrogen and water to produce hydronium ions is very exothermic: H+ + H2O --> H3O+ + heat, hence the net result is a very exothermic reaction as the amount of energy released (in the form of heat) by the ionisation of sulfuric acid is greater than the amount of energy required to ionise the molecule.

Next question:

Describe the processes that are used to monitor eutrophication in water bodies (4 marks)

 

[QZP]

2012 HSC: Describe the process of monitoring waterways for eutrophication. (3)
Sample solutions don't go into the Kjeldahl method/colorimetry so I don't understand what we are expected to know. Anyone want to have a go at it without using aforementioned methods?

 

[photastic]

2012 HSC: Describe the process of monitoring waterways for eutrophication. (3)
Sample solutions don't go into the Kjeldahl method/colorimetry so I don't understand what we are expected to know. Anyone want to have a go at it without using aforementioned methods?

WTH is this?

 

[enigma_1]

WTH is this?

it's a method used to test the concentration of nitrates

 

[QZP]

Kjeldahl method for nitrates, colorimetry for phosphates.

 

[QZP]

I doubt we have to know it though... this dotpoint is definitely the worst one. No one knows what HSC wants and textbooks are way too excessive

 

[faisalabdul16]

Kjeldahl method for nitrates, colorimetry for phosphates.

Kjeldahl method is not in syllabus.

 

[faisalabdul16]

This is what my friend told me yesterday.


To test for eutrophication:

Phosphate to nitrogen ratio is 1:10

To test for nitrate:
React nitrate with a reductant to get nitrite ions, then react the nitrite with a colour reagent to get an azo-purple dye. Then you use a colourometer calibrated using standard solutions to determine the nitrate content.

To determine the amount of organic nitrogen, you convert the organic nitrogen to ammonia, then titratie the ammonia with standardised HCL.

To test for phosphate:
Add ammonium molybdate and ascorbic acid, heat in a water bath at 90 degrees, and you'll get a blue complex solution. Then use a calibrated colourometer with standard solutions to measure the concentration of phosphate.

To test for organic phosphorus, change the phosphorus to phosphate then use method above.

 

[enigma_1]

HSC chemistry is so corrupted I swear :/

 

[QZP]

This is what my friend told me yesterday.


To test for eutrophication:

Phosphate to nitrogen ratio is 1:10

To test for nitrate:
React nitrate with a reductant to get nitrite ions, then react the nitrite with a colour reagent to get an azo-purple dye. Then you use a colourometer calibrated using standard solutions to determine the nitrate content.

To determine the amount of organic nitrogen, you convert the organic nitrogen to ammonia, then titratie the ammonia with standardised HCL.

To test for phosphate:
Add ammonium molybdate and ascorbic acid, heat in a water bath at 90 degrees, and you'll get a blue complex solution. Then use a calibrated colourometer with standard solutions to measure the concentration of phosphate.

To test for organic phosphorus, change the phosphorus to phosphate then use method above.

And this is meant to be in the syllabus?

 

[teridax]

HSC chemistry is so corrupted I swear :/

y

 

[Queenroot]

It actually is corrupt and has only some relation to higher level chemistry. And almost no arithmetic.

 

[faisalabdul16]

It actually is corrupt and has only some relation to higher level chemistry. And almost no arithmetic.

Bold part - calculations? Explain what you mean pls

 

[Queenroot]

Bold part - calculations? Explain what you mean pls

Yeah pretty much. There's hardly any calculations in the HSC lol.

 

[faisalabdul16]

Yeah pretty much. There's hardly any calculations in the HSC lol.

haha that's good. Calculations is the best, memorising is the worst.

 

[zhertec]

This is what my friend told me yesterday.


To test for eutrophication:

Phosphate to nitrogen ratio is 1:10

To test for nitrate:
React nitrate with a reductant to get nitrite ions, then react the nitrite with a colour reagent to get an azo-purple dye. Then you use a colourometer calibrated using standard solutions to determine the nitrate content.

To determine the amount of organic nitrogen, you convert the organic nitrogen to ammonia, then titratie the ammonia with standardised HCL.

To test for phosphate:
Add ammonium molybdate and ascorbic acid, heat in a water bath at 90 degrees, and you'll get a blue complex solution. Then use a calibrated colourometer with standard solutions to measure the concentration of phosphate.

To test for organic phosphorus, change the phosphorus to phosphate then use method above.

Read the sample answer for the question and they used this + BOD so it should be ok for hsc.

 

[SuchSmallHands]

Alright, lets go

- Before WWI, one of the main source of ammonia for use as fertilisers was from saltpetre from Chile.
- During WWI, these supplies were cut to Germany and thus, they required a new method of obtaining ammonia for essential food production.
- The Haber Process provided a way for ammonia to be formed from gaseous nitrogen and hydrogen and was essential at that time for Germany, as it provided fertiliser and thus food for their population, preventing mass starvation.
- Ammonia could also be used to produce nitric acid which was in turn used to make explosives and so the discovery aided Germany's war efforts.
- Therefore, Haber's discovery was essential for Germany as it provide food for its people and weapons for the war, essentially prolonging WWI.
- However, after the war, this new method of obtaining ammonia was adopted worldwide and today the sheer importance of the discovery is evident as the Haber Process is the main source of ammonia, which is used for fertilisers in order to feed our continually growing population. This high demand for ammonia and fertilisers would not have been able to be provided by natural sources such as saltpetre and guano and thus the importance of the Haber's discovery.

Said that in my trial, got absolutely smashed for it don't even go there. Apparently you're supposed to say 'nitrates' there instead of 'ammonia'. I seriously lost two marks for this shit.

 

[QZP]

Read the sample answer for the question and they used this + BOD so it should be ok for hsc.

What question? The one I asked? Because they don't... that's why I asked